1. Field of the Invention
The present invention relates to a plasma processor used in a process of manufacturing semiconductors, thin film devices, and the like.
2. Description of the Prior Art
In a process of manufacturing semiconductors, thin film devices, and the like, an etching apparatus or a resist asher using microwave energy is used.
FIG. 5 shows a conventional resist asher, in which a vacuum chamber 1 has a gas introduction inlet 2 and an exhaust port 3 and is partitioned by a quartz plate 4 sealed at the edge with an O-ring. The inside of the vacuum chamber 1 is kept under reduced pressure and is provided with a table 7 for loading thereon a sample 8. At the upper portion of vacuum chamber 1 is provided a chamber 6 for trapping therein microwaves. A single waveguide 5 for transporting the microwaves from a microwave generating source (not shown) into the chamber 6 is connected with the upper portion of chamber 6.
A resist is etched as follows: First, of all, oxygen is pumped into the vacuum chamber 1 at a flow rate of 50 standard cubic centimeters per minute (SCCM) through the gas introduction inlet 2 so as to keep the pressure in the vacuum chamber 1 at 0.5 Torr. Microwave energy is applied from the microwave generating source (not shown) into the chamber 6 through the waveguide 5 with a power of 400 W to generate plasma for etching the resist. The etching speed for the resist is 3000 .ANG./min at 20.degree. C. and 8000 .ANG./min at 200.degree. C. depending upon the temperature of the sample table 7. The uniformity of etching is found to be accurate within .+-.15% per 6 inch wafer.
Such an apparatus with the above-mentioned construction has a problem in that it is difficult to etch uniformly and at a high speed with a substrate having a diameter of 8 inches or more, because the chamber must be of resonance construction in order to efficiently introduce the microwave energy thereinto, which causes difficulties in freely designing the construction of the apparatus.